Scientists cut million-year natural process to convert algae into crude oil to about an hour

Scientists cut million-year natural process to convert algae into crude oil to about an hour

Engineers have sped up a naturally occurring process to make crude oil from algae from about a million years to just minutes.
Researchers at the Department of Energy’s Pacific Northwest National
Laboratory pumped a slurry of wet algae into a chemical reactor, which
then subjects the biological material to very hot water under high
pressure to tear it apart and convert it into liquid and gas fuels.
The resulting crude oil can then be conventionally refined into
aviation fuel, gasoline or diesel fuel, the researchers reported in the
journal Algal Research.
The
team’s experiments converted more than 50 percent of the algae’s carbon
into crude oil, sometimes up to 70 percent, in about one hour and
created nothing more hazardous than an odor of dirty socks, rotten eggs
and wood smoke from the processed biological material.
In fact, the leftover water and nutrients such as nitrogen, phosphorus and potassium can be recycled to grow more algae.
Algae has long been considered a potential source of biofuel and has
been produced by several companies on a research scale, but the fuel was
projected to be prohibitively expensive.
However, the recently developed technology uses a number of methods
to reduce costs and has been licensed by the Utah-based Genifuel Corp.,
which is building a pilot plant with an industrial partner.
The process works an algae slurry that contains up to 90 percent
water, unlike most current processes that used dried algae, and cuts
costs significantly by eliminating the need for time and energy used to
dry out the biomaterial.
“Not having to dry the algae is a big win in this process; that cuts
the cost a great deal,” said Douglas Elliott, who led the PNNL research
team. “Then there are bonuses, like being able to extract usable gas
from the water and then recycle the remaining water and nutrients to
help grow more algae, which further reduces costs.”
Other groups have tested similar processes, but most of that work was done one batch at a time.
The PNNL system runs continuously and processes about 1.5 liters of
algae slurry per hour in the laboratory reactor, and scientists think
this can be accomplished on a commercial scale.
The method also eliminates the need for complex processing with
solvents such as hexane to extract energy-rich oils from the algae.
The system runs at more than 660 degrees Fahrenheit at about 3,000
pounds per square inch, combining processes known as hydrothermal
liquefaction and catalytic hydrothermal gasification.
The system isn’t easy or cheap to build, but Elliott said cost savings later in the process justified the investment.
“It’s a bit like using a pressure cooker, only the pressures and
temperatures we use are much higher,” Elliott said. “In a sense, we are
duplicating the process in the Earth that converted algae into oil over
the course of millions of years. We’re just doing it much, much faster.”Watch this video report about the process posted online by PNNLgov: